Scope_of_Work_Summary.pdf

Port Huron Federal Building and U.S. Courthouse Cupola Repairs 1

PORT HURON FEDERAL BUILDING

AND U.S COURTHOUSE

Undated image taken before the turn of the twentieth century.

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2 Port Huron Federal Building and U.S. Courthouse Cupola Repairs

PORT HURON FEDERAL BUILDING

AND U.S COURTHOUSE

526 WATER STREET,

PORT HURON, MI

M ili ta ry S tr e e t

Port Huron Federal Building and U.S. Courthouse Cupola Repairs 3

Mast and Guy Wires

Base

Entablature

Standing Seam Copper Roof

Balustrade

Drum

Upper Cornice

Dormer

Upper/Flat Cupola Roof (Liquid applied membrane over flat lock metal roof)

Project Description The following pages provide a summary of work for the Cupola Restoration Project at the Federal Building and U.S. Courthouse in Port Huron, Michigan. The work involves the cupola envelope and addresses the issues of material deterioration and water infiltration. The project limits extend from the base of the cupola to the top of the mast. The majority of the work will be completed during the hours of 7:00am-4:30pm. Loud and disruptive work will be completed after normal business hours. The work includes the following items:

1) Removal of existing paint and application of a new high performance coating on the mast.

2) Removal or exiting roof and installation of a new membrane roof on the top of the cupola.

3) Removal of existing paint on all wood surfaces. Preserve, repair and replacement of deteriorated wood elements and the application of high performance paint to all exterior woodwork within the extent’s of the work.

4) Removal and replacement of the standing seam copper roof.

5) Removal of the existing paint on the metal panels at the base of the cupola. Preserve, repair, and patch the panels and the application of high performance paint to the base of the cupola.

Proposed treatments have been developed with the intention of preserving existing fabric to the extent possible while improving the longevity and performance of the envelope materials through repair and replacement where necessary. All work will be required to comply with the Department of The Interior’s Standard for Rehabilitation.

Mast and Guy Wires The mast is an important character defining feature of the building and will be protected in place during construction. The guy wire attachments will be temporarily detached while the balustrade and roof work are completed. Surface corrosion will be removed and a new high performance painted finish will be applied to the mast and associated components. The guy wire anchors will be reinstalled in their original location once the roof work is complete.

Left: View of mast and guy wire connections. Center: Detail view of mast base and lightning protection cable where they penetrate the flat roof of cupola. Right: Typical guy wire connection.

Balustrade

The existing balustrade will be removed and replaced. The removal of the balustrade will be necessary to reroof the top of the cupola, the balustrade will be disassembled, disposed of and new will be installed to match the original building balustrade. All loose joinery will be tightened and a new high performance paint system will be applied to the balustrade. A metal cap flashing will be installed over the top rail to protect the sky-facing joints. The metal cap will be painted to match the rest of the balustrade so that it blends visually with the wood elements and is not visible from grade.

Cupola Roof (Upper/Flat Membrane Roof)

The existing roof will be require the removal of the existing membrane roofing and earlier flat lock metal panels, preparation of the substrate and decking and the installation of a new fully reinforced cold fluid applied polyurethane liquid resin roof with waterproofing membrane and flashing system.

View of balustrade and upper cornice.

View of flat roof on top of cupola.

Cupola Roof (Standing Seam Copper)

The contractor will be responsible for replacing the existing copper roof with a new copper roof and to repair the wood ribs and upper cornice. A new standing seam copper roof will be installed to visually match the existing roof and be consistent with conditions portrayed in historic images of the Courthouse.

Removal of the existing copper roof will likely reveal areas of deteriorated wood sheathing. Allowances will be made to account for these concealed and unknown conditions.

Mast guy wire anchors will be reinstalled in their original locations. The existing ribs will be repaired and painted. The existing ribs are anticipated to be historic and will be repaired.

Dormers

The existing cap flashing on sky-facing surfaces will be removed and replaced. Areas of wood rot will be repaired according to a tiered treatment approach where small areas of rot will be filled with a wood consolidate and stabilization product and larger areas of rot will be repaired by splicing in new wood that matches the profile and species of the existing material. Where rot or damage is so extensive that it is no longer practicable to complete a localized or Dutchman repair, the member will be replaced in its entirety with new wood matching the profile and species of the existing wood.

The split sashes will be repaired in order to maintain the continuity of the envelope. In order to make repairs, the interior head and jamb timbers will be removed to access the sash. Glazing compound and glazing will be removed and then the splits repaired by gluing and doweling. Following sash repair, the existing glazing will be reinstalled and new glazing compound applied. The sash will then be reinstalled in the openings, sealed, and the interior timber framing reinstalled.

The existing painting will be removed and a high performance paint finish will be applied to all exposed wood surfaces on the exterior.

Exterior view of typical dormer. Interior elevation at dormer window sash. Note split in sash at head and sill. This condition affects all four windows.

Entablature

Treatment of the entablature will focus on tightening loose trim and joinery, repairing isolated rot and applying a high performance paint system to the wood. A tiered approach to wood repair will be implemented that begins with the gentlest or least invasive means and is increased to address more severe deficiencies or condition issues.

General view of wood drum. This portion of the cupola is in relatively good condition.

Drum Treatment of the drum will focus on paint removal to the extent necessary to evaluate the underlying wood, repairing areas of wood rot, and reworking or filling gaps at trim elements to seal the building envelope against moisture infiltration. The same tiered approach to wood repair described above in the dormer treatment narrative will be specified. A high performance paint system will be applied to the wood following the repairs.

Base

Proposed Treatment Treatment of the corroded panels will require a careful and meticulous repair process that will need to be completed by a highly skilled craftsman in the restoration of historic sheet metal. The repair will require complete removal of the sealant, caulk, and painted finish to clean, bare metal. A corrosion inhibiting primer and thin coating of urethane sealant will be applied to each seam followed by the application of a high performance paint system.

Above: General view of copper bearing steel panel cladding at base of cupola. Right: Insets showing typical failure of seams and application of sealants and caulks to prevent water infiltration.

Typical condition of metal panel seams. Significant corrosion of metal panels at seam.